| 摘要 |
PROBLEM TO BE SOLVED: To provide a riser with a spiral guide passage, which allows sewage flowing into a lower portion of a riser main body to easily form vortexes flowing down along the spiral guide path, whereby surplus energy is effectively absorbed. SOLUTION: The riser 1 with the spiral guide path is constructed by arranging a first air core pipe and a first spiral guide path 1 in an upper portion of the straight pipe riser main body 11. Further, the riser 1 includes a second spiral guide path 16 which is arranged in a lower portion 11c of the riser main body 11, and then a second air core pipe 17 is disposed at an upper end of the second spiral guide path 16.
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